.TH std::ranges::slide_view::size 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::ranges::slide_view::size \- std::ranges::slide_view::size

.SH Synopsis
   constexpr auto size()                     (since C++23)
     requires ranges::sized_range<V>;
   constexpr auto size() const               (since C++23)
     requires ranges::sized_range<const V>;

   Returns the number of elements.

   Let base_ and n_ be the underlying view and "window size" respectively.

   Equivalent to:

 auto sz = ranges::distance(base_) - n_ + 1;
 if (sz < 0)
     sz = 0;
 return __to_unsigned_like(sz);

.SH Parameters

   \fI(none)\fP

.SH Return value

   The number of elements. Equals to 0, if the number of elements (ranges::size(base_))
   in underlying view base_ is less than "window size" n_.

.SH Example


// Run this code

 #include <forward_list>
 #include <iostream>
 #include <list>
 #include <ranges>

 int main()
 {
     constexpr static auto v = {1, 2, 3, 4, 5, 6};

     constexpr int width1{4};
     constexpr auto view1{std::views::slide(v, width1)};
     static_assert(view1.size() == 3);
     static_assert(view1.size() == (v.size() - width1 + 1));

     constexpr int width2{8};
     constexpr auto view2{std::views::slide(v, width2)};
     // window is too wide, so view2 has no elements:
     static_assert(view2.size() == 0);

     std::forward_list forward_list = v;
     const auto view3{std::views::slide(forward_list, width1)};
 //  auto x = view3.size(); // error: sized_range constraint is not satisfied

     std::list list = v;
     const auto view4{std::views::slide(list, width1)};
     std::cout << view4.size() << '\\n'; // prints 3
 }

.SH Output:

 3

.SH See also

   ranges::size  returns an integer equal to the size of a range
   (C++20)       (customization point object)
   ranges::ssize returns a signed integer equal to the size of a range
   (C++20)       (customization point object)
